The Effect of Simethicone Administration Timing and Pre-Examination Modified Position Changes on Defoaming Efficacy During Gastroscopy

Background: Gastroscopy remains a cornerstone in diagnosing upper gastrointestinal tract diseases. However, intragastric foam impairs mucosal visualization, potentially reducing early lesion detection rate. Simethicone is widely used as a defoaming agent in clinical practice, yet its efficacy may be influenced by administration methods and timing. Aims: To investigate the effects of body position changes and waiting time after simethicone administration on defoaming efficacy during gastroscopy. Methods: A prospective study was conducted at the Endoscopy center, Hospitol, Macau, Jul–Aug 2024. Patients scheduled for gastroscopy were divided into a control group (supine position) and an experimental group (body position changes). The experimental group was further subdivided into Group A (traditional sequence: right lateral, supine, left lateral positions, each maintained for 5 min) and Group B (modified sequence: right lateral position for 5 min, followed by alternating head-down/head-up positions for 1 min each, then left lateral position for 3–5 min). The control group was additionally stratified by waiting time post-simethicone administration (≤15 min, 16–30 min, ≥31 min). The primary outcome was mucosal clarity score assessed with the KUO score; secondary outcomes included examination time and polyp detection rate. Results: Group B demonstrated significantly better mucosal clarity compared with both the control group and Group A (P<0.001). Among control patients, those examined within 15 minutes post-medication showed superior defoaming efficacy compared with those examined after 31 minutes (P<0.05). Examination times were comparable across groups. No significant association was observed between mucosal clarity and polyp detection rates. Conclusions: Combining optimized body position changes with appropriate timing post-simethicone administration significantly improves mucosal visualization during gastroscopy. This strategy provides a simple, cost-effective approach to enhance diagnostic performance and is recommended for broader clinical application.